NZ volcano eruptions 'good for tourism'

NEW Zealand tourism operators are hoping the "significant probability" that Mt Tongariro will erupt again in the next week could be good for them.

Tongariro's Te Maari crater erupted for about five minutes on Wednesday afternoon, emitting a plume of ash and gas up to 4km into the air.

It sent trampers on the popular Tongariro Alpine Crossing scurrying down the mountain and forced the cancellation of Air New Zealand flights to regional airports at Taupo, Rotorua and Gisborne.

But in an area known for its volcanic activity, the international publicity from an eruption can be helpful - provided it doesn't go on too long.

"For now we're in the spotlight, and sometimes that can turn out to be a positive," Visit Ruapehu general manager Mike Smith said.

"If it's short term, which we all hope it is, then these things have a funny way of working out in a positive way.

"If it's longer term, and particularly over a number of weeks, then it's more challenging."

The volcano burst into life for the first time in 115 years in August, when an eruption sent rocks smashing into nearby Ketetahi Hut used as trampers' accommodation, but only ash and gas were ejected on Wednesday.

Civil Defence says the threat related to the eruption has passed and a national advisory has been cancelled.

"However, GNS Science indicates that there remains a significant probability of sudden eruption within the next week," Civil Defence said in a statement.

This may prompt Civil Defence to issue a new advisory or warning.

GNS Science says although volcanic activity on Tongariro has remained at a low level since the eruption, there had been no warning observed before it occurred.

"Future eruptions could also occur with little or no warning," it said.

The volcanic alert level stands at two, signalling minor eruptive activity and the aviation colour code had been decreased from red to orange, indicating that a volcanic eruption is under way but with little or no ash being produced.

Meanwhile, Air New Zealand has resumed flights to and from Rotorua, Taupo and Gisborne as the ash cloud from the eruption was cleared to the east of the country.

The Alpine Crossing remains off-limits to trampers for at least three days.

Last week, GNS warned there was increased activity underneath nearby Mt Ruapehu but a link between the two has been dismissed.